The invention relates to a ball-cock made of plastic parts with a rotatable, essentially spherical shut-off element, provided with a passage, accommodated in a housing of which the inside wall at the first housing end determines a nesting place for a sealing ring interacting with the shut-off element and which at the other end is shut off by an end flange of which the inside wall also determines a nesting place for a sealing ring interacting with the shut-off element, and which housing also has a guide which is situated at right angles to the passage for the accommodation of a control spindle which is in engagement by the first end with the shut-off element, and the second end of which interacts with a control element.